In an effort to find new energy sources, fuel cells using an electrochemical reaction to generate electricity are becoming an attractive energy alternative. Fuel cells offer low emissions, high fuel energy, high conversion efficiencies, and low levels of noise and vibration. Proton electrolyte membrane fuel cells (PEMFCs) have been identified in many industries, such as the automotive industry, as an especially advantageous fuel cell design, and therefore, the development of new and improved materials and components inside the PEMFC is ongoing.
In particular, high temperature PEMFCs operational above 120° C. with low humidification or without humidification, can offer several advantages such as anode tolerance to significant quantities of carbon monoxide poisoning, operability without humidification, electrode kinetics enhanced by high temperatures (e.g. 120° C.), elimination of cathode flooding, and ease of thermal management. While conventional electrodes for PEMFCs are mainly focused on Nafion®-based electrodes (e.g., commercial E-TEK® electrodes), Nafion®-based electrodes are only operable for low temperature PEMFCs (e.g., operational below 100° C.), and are reliant on external or internal (e.g., self-humidifying) humidity for proton transfer.
Due to the issues with Nafion®-based electrodes, alternative polymers which facilitate operation at high temperature without humidity have been studied. For example, a blend of polybenzimidazole (PBI) and phosphoric acid has been identified as a feasible composition for operation at high temperatures. The blend of PBI and phosphoric acid performs the function that water provides in Nafion®-based electrodes (i.e., proton transfer), thus humidification is not necessary. However, to achieve acceptable proton transfer and conductivity, the PBI/phosphoric acid blend requires substantial amounts of phosphoric acid (e.g., 3.5 to 7.5 H3PO4 per PBI repeating unit), which results in acid leeching and corrosion of the membrane electrode assembly. As a result, improved compositions for catalyst layers of fuel cell electrodes that maximize proton transfer and conductivity while minimizing corrosion is highly desirable.